Isolation, purification and the physicochemical properties of the monoamine oxidase from the myocardium

Abstract: A preparation of monoamine oxidase, purified 20-fold with a yield of 20%, was isolated from mitochondrial fraction of bovine heart after treatment with a nonionic detergent Triton X-100 combined with sonication followed by gel filtration on Sephadex G-200 and Sepharose 6B. By the data of gel filtration molecular weight of the preparation was 330,000. Two protein fractions with molecular weights of 84,000 and 90,000 were found using disc electrophoresis in 7.5% polyacrylamide gel containing 2-mercaptoethanol and sodium dodecylsulfate. The purified enzyme contained 8.6 mol of SH-groups per 100,000 daltons of protein, 4.1 micrograms of inogranic phosphate per 1 mg of protein; Km value was 37.6 microM for benzylamine as a substrate. In experiments with elective inhibitors of monoamine oxidases the enzyme from bovine heart muscle exhibited high sensitivity to the inhibitory effect of deprenyl, which characterises the monoamine oxidases of the B type.